CA1157571A - Isolation amplifier - Google Patents
Isolation amplifierInfo
- Publication number
- CA1157571A CA1157571A CA000367616A CA367616A CA1157571A CA 1157571 A CA1157571 A CA 1157571A CA 000367616 A CA000367616 A CA 000367616A CA 367616 A CA367616 A CA 367616A CA 1157571 A CA1157571 A CA 1157571A
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- Canada
- Prior art keywords
- rectifier
- amplifier
- winding
- signal
- input
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/38—Dc amplifiers with modulator at input and demodulator at output; Modulators or demodulators specially adapted for use in such amplifiers
- H03F3/387—Dc amplifiers with modulator at input and demodulator at output; Modulators or demodulators specially adapted for use in such amplifiers with semiconductor devices only
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
Abstract
935.042 WILLIAM H. MORONG, III
IMPROVED ISOLATION AMPLIFIER
ABSTRACT OF THE DISCLOSURE
An isolation amplifier comprising an input section coupled by a multi-winding transformer to an output section.
A blocking oscillator produces in the transformer a signal comprising a positive power pulse followed by a negative flyback pulse. The flyback pulse magnitude is modulated by a half-wave diode-capacitor rectifier circuit which supplies negative supply current to an amplifier in the input section.
Other half-wave diode-capacitor rectifier circuits in the input section develop (1) a positive supply voltage for the amplifier, (2) a negative feedback signal for the amplifier, and (3) a level-shifting voltage to be combined with the feed-back signal. The output section includes additional half-wave diode-capacitor rectifier circuits to develop a demodu-lation signal derived from the flyback pulse, and a bias voltage to be combined with that signal to develop an input signal for the output amplifier.
IMPROVED ISOLATION AMPLIFIER
ABSTRACT OF THE DISCLOSURE
An isolation amplifier comprising an input section coupled by a multi-winding transformer to an output section.
A blocking oscillator produces in the transformer a signal comprising a positive power pulse followed by a negative flyback pulse. The flyback pulse magnitude is modulated by a half-wave diode-capacitor rectifier circuit which supplies negative supply current to an amplifier in the input section.
Other half-wave diode-capacitor rectifier circuits in the input section develop (1) a positive supply voltage for the amplifier, (2) a negative feedback signal for the amplifier, and (3) a level-shifting voltage to be combined with the feed-back signal. The output section includes additional half-wave diode-capacitor rectifier circuits to develop a demodu-lation signal derived from the flyback pulse, and a bias voltage to be combined with that signal to develop an input signal for the output amplifier.
Description
l ~335 . O~Z
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BACKGROIIND OF THE INVENTIO~ I
. I
1. Field of the Invention This invention relates to isolation ampliiers, i.e.
!amplifiers having an input section which is galvanically ¦isolated from all other portions of the equipment. More Iparticularly, this invention relates to such isolators wherein ¦Ithe input and output sections are coupled by a single trans-former serving the dual functions of supplying energizing ipower to the input section and carrying signal information to l~the output section.
,,.
~l2. Description of the Prior Art il ' I, A wide variety of iso~a~ors have been employed in ¦¦the past for applications such as developing me surement sig-. ¦nals for industrial process control systems, maXing medical ¦measurements of the human body, and so on. A number of such isolators have employed a single transformer for effecting ¦non-conducti~e coupling between the input section and other ¦portions of the isolator. For example, U. S. Patent 3,988~690l 1 ,¦shows a design wherein such a single transformer includes l I
?O l¦three separate windings. In that arrangemellt, the power Idrawn through the transformer by the input section varies in ,1 ~i .
1 1157571 935.~2 accordance with -the applied input signal and this power vari-ation is detected in the output to produce a corresponding output signal.
U. S. Patent 4,066,974 is directed to an arrangement which uses a transformer li~ited to only two windings, i.e.
a single primary winding and a single secondary winding. Thel econdary winding is connected al-ternately to a d-c voltage ¦
and to a high-impedance. The d-c voltage connection couples j energizing power through the transformer to develop a d-c Ipower supply voltage in the input section, and the following high impedance connection produces a reverse~polarity flyback pulse which is modulated by the signal applied to the input section. The magnitude of the flyback pulse is detected in the output section to produce a corresponding output signal. l A subsequent development, described in U. S. Patent 4,152,660,' ~adds to U. S. Paten~t 4,066,974 the concept of utilizing the d-c power pulse in the transformer to produce a steady d-c ~voltage in the output section for energizing amplifier circuitry .
in that output section. I
. !
, - , I .
~0 Experience with devices such as described in the above patents has shown that all suffer from important disadvantages, ~particularly with respect to performance characteristics such !
as drift of output signal with changes in temperature, non-linearity of the relationship between input and output, and ~,changes in gain with temperature.
. ,1 1 ,'.
"
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, ~
li SUMMARY OF THE INVENTION
il ,.
'~ It is a principal o~ject of the present invention td " provide an improved transformer-coupled signal isolator of Il the type utilizing alterna~ing power and flyback pulses.
I Still another object of this invention is to provide such an I isolator which is relatively inexpensive to manufacture, yet ', reliable in operation, ll .
1, .
1 In accordance with an important aspect of the inven-,~ tion, significantly improved performance is achieved by meansl ¦ of unique circuit arrangements effecting inherent matching o~
the variations of selected corresponding d-c signals in the isolator circuitry. An isolator of the type described herei makes use of an arrangement wherein voltages of relatively I large magnitude are connected in subtractive opposition to I
, develop a resulting difference voltage. In such an arrangement, small non-equal variations in the opposed voltages can produce relatively large percentage changes in the net difference ¦
voltage, and this in turn can cause excessive erxors in the I
li output of the isolator, e.g. due to changes in am~ient temper- ¦
20 li ature. It has been found, however, that such variations can j be substantially reduced by employing simplified matched circuit configurations which assure that selected pairs of 'i d-c signals in the isolator closely -track one another, thereby I to minimize differential efrects, and particularly to reduce ¦
, variations in 1solator performance with changes in temperatur Other objects, aspects and advantages of the invention will in part be pointed out in, and in part apparent from, the ~: O ~.
~ 57571 935 ~
, following detailed description considered together with the accompanying drawing.
BRIEF DESCRIPTION OF THE D~AWING
' FIGURE 1 is a schematic diagram OL a preferred em-,lbodiment of the present invention~
~'I .
I DESCRIPTIO~ OF THE PREFERRED E~BODIMENT .
¦, Referring now to Figure 1, the presently preferrea isolator in accordance with the invention comprises input and ` ioutput sections 10 and 1~ coupled by a trans~ormer 14 having 'one single-turn winding and five identical 8-turn windings.
The output section 12 includes a free-running inductively- , coupLed blocking oscillator generally indicated at 16. This ¦
"oscillator comprises a transistor 18 with its base connected !ito the single-turn winding 20 and its collec~or connected to ,one of the 8-turn windings 22.
.
.l As indicated in the waveform shown directly above ¦Ithe transformer 14 in Figure 1, the blocking oscillator cycle I ¦
iincludes a positive "on" pulse, produced by the power supply 'Ivoltage, fo3,10wed by a negative "flyback" pulse which is unclamped in the oscillator As will he explained, the magni-¦tude of the flyback pulse is modulated in accordance with the ,iinput signal applied to the input section 10 of the isolator.
,,1 1 .1 . I , " ~
~ _5_ 1 , 1 935-04~ 1 57~ l The oscillator on-time is a function of the trans- I
former saturation characteristics, i.e. the time to saturation, whereas the off-time is a function Qf an RC time-constan-t. In one preferred arrangement, the oscillator frequency was approx-imately 200 kH~, with a 0.5 microsecond "on" time and a 4.5 microsecond "off" time. Suitable saturation characteristics jwere obtained in a core made of Ferroxcube 3C8 ferrite.
In the input section 10 of the isolator, there are four half-wave rectifier circuits 30, 32, 34, 36 coupled to Ithe transformer 14. Each of these rectifier circuits consists ~of a diode in series with a filter capacitor. Three of these ! rectifier circuits 30, 32, 34 are connected across a single !
transformer winding 38, but as will be explained the four-th rectifier circuit 36 is connected across a separate trans-former winding 40. Two of the rectirier circuits 30~ 34 are poled to respond to the negative '~flyback" pulse developed in~
the transformer by the blocking oscillator 16 The other two rectifier circuits 32, 36 are oppositely poled, to respond to - the positive "on" power pulse of the oscillator output wave-'form. All of the rectifier circuits develop across their ~respective filter capacitors d-c voltages corresponding to the ,magnitude of whichever pulse (flybacX, or power) they are poled to respond to.
. I .
" ! ~
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1, .
~ 157~71 935.0~2 .1 , The negative d-c voltage developed across the filter capacitor 42 of the first hal-wave recti~ier circuit 30 is applied to the negative supply terminal of an opera-tional amplifier 44, e.g. an IC chip of the typ~ conventionally identified as a 308, and manufactured by a nu~ber of companies.
,The positive supply terminal of this amplilier receives the positive d-c voltage (about 15 volts) developed across the filter capacitor 46 of the second rectifier circuit 32. The Iamplifier input 48 is connected through a resistor (lOOK ohms) I`to the input terminal 50 of the isolator, to receive the ap- ¦
l~plied input signal. The amplifier output terminal 52 is con-nected through a capacitor 54 back to the amplifier input 48 to effect system frequency compensation. The output terminal '52 also is connected to input common 58 by a small resistor l'56 (470 ohms) to accommodate the desired a-c feedback through Icapacitor 5~ while completing the d-c negative supply current return path through the amplifier output suDstantially at common potential.
~ .
' As the input signal applied to the amplifier changes, 'there will be a corresponding change in the d-c supply current "drawn from the negative rectifier voltage-supply circuit 30.
The supply current drawn from that rectirier circuit loads I
down the flyback stroke of the oscillator 16, such that change~
iin the supply current correspondingly modulate the magnitude ~!f the flyback pulse (as indicated in dotted lines in the ,waveform shown in Figure 1). Thus the rectirier circuit 30 115~571 ~35 04~ 1 ' .
~Ifunctions as a modulator, under control of the applied input ¦Isignal This arrangement wherein the negative supply current is used to vary the load on the modulator 30 eliminates the 'need for a separate and additional modulator transistor driven ¦,by the a~lplifier output signal. ' .
The third hal~-wave rectifier circuit 34 is loaded .
by a resistor 60 (220K ohms) returned to the positive supply terminal for the amplifier 44, and produces a negative d-c ~voltage proportional to the magnitude of the modulated flybac~
Ipulse in the transformer 14. That is, the rectifier circuit I
¦34 demodulates the flyback pulse magnitude as controlled by .
the modulator circuit 30. The negative d-c voltage produced I .
by the third rectifier circuit 34 is used as a negative feed- I , ¦back signal for the amplifier 44, to effect correspondence between the amplifier input signal and the modulation signal ~developed by the first rectifier circuit 30. 1 To assure that this feedback signal is at the correct .
voltage level for the input circuit of the 2mpllfier 44, the Inegative d-c signal from the third rectifier circuit 34 is ~Iconnected in series with a positive d-c level-shifting voltagei ¦
j(about 15 volts) produced by the fourth half-wave rectifier circuit 36. This rectifier circuit is loaded by a resistor ~i62 (lOOK ohms) connected directly across the filter capacitor.. I
~The combined voltage signal developed by the two rectifier ~ ¦
icircuits 34, 36 is connected through a feedback resistor 64 1 1 ii . 1.
!l l 1S7571 935. 0~2 "
!`
(~40K) to the input 66 of the amplifier. With this feedback ar~angement, the negative supply current of the amplifier drawn from the modulator rectifier circuit 30 is automatically controlled so as to clamp the flyback pulse to the correct S l, magnitude such that the sum of the voltages produced by the two upper rectifier circui-ts 34 and 36 equals the isolator input voltage.
l .
The isolator as described above has unity gain in ' the input section 10. However, the isolator is arranged so ll that the input section can develop a gain greater than unity~¦
- This is controlled by connecting an external resistor (not shown) between the gain terminal 70 and the input common line 58. With that connection, the amplifier gain will be propor-, tional to the ratio o~ esistances of the feedback resistor. I
64 and the external resistor. I
l It should particularly be noted that in the arranger ,~ ment described above, the modulator circuit 30 and the demod~
- ulator circuit 34 are coupled to the same transformer winding - ~' 38. It has been found that this use of the same winding for i
I ~IL5757~
.
~' I
BACKGROIIND OF THE INVENTIO~ I
. I
1. Field of the Invention This invention relates to isolation ampliiers, i.e.
!amplifiers having an input section which is galvanically ¦isolated from all other portions of the equipment. More Iparticularly, this invention relates to such isolators wherein ¦Ithe input and output sections are coupled by a single trans-former serving the dual functions of supplying energizing ipower to the input section and carrying signal information to l~the output section.
,,.
~l2. Description of the Prior Art il ' I, A wide variety of iso~a~ors have been employed in ¦¦the past for applications such as developing me surement sig-. ¦nals for industrial process control systems, maXing medical ¦measurements of the human body, and so on. A number of such isolators have employed a single transformer for effecting ¦non-conducti~e coupling between the input section and other ¦portions of the isolator. For example, U. S. Patent 3,988~690l 1 ,¦shows a design wherein such a single transformer includes l I
?O l¦three separate windings. In that arrangemellt, the power Idrawn through the transformer by the input section varies in ,1 ~i .
1 1157571 935.~2 accordance with -the applied input signal and this power vari-ation is detected in the output to produce a corresponding output signal.
U. S. Patent 4,066,974 is directed to an arrangement which uses a transformer li~ited to only two windings, i.e.
a single primary winding and a single secondary winding. Thel econdary winding is connected al-ternately to a d-c voltage ¦
and to a high-impedance. The d-c voltage connection couples j energizing power through the transformer to develop a d-c Ipower supply voltage in the input section, and the following high impedance connection produces a reverse~polarity flyback pulse which is modulated by the signal applied to the input section. The magnitude of the flyback pulse is detected in the output section to produce a corresponding output signal. l A subsequent development, described in U. S. Patent 4,152,660,' ~adds to U. S. Paten~t 4,066,974 the concept of utilizing the d-c power pulse in the transformer to produce a steady d-c ~voltage in the output section for energizing amplifier circuitry .
in that output section. I
. !
, - , I .
~0 Experience with devices such as described in the above patents has shown that all suffer from important disadvantages, ~particularly with respect to performance characteristics such !
as drift of output signal with changes in temperature, non-linearity of the relationship between input and output, and ~,changes in gain with temperature.
. ,1 1 ,'.
"
g35 ~ 0~2 ~S7~71 .
, ~
li SUMMARY OF THE INVENTION
il ,.
'~ It is a principal o~ject of the present invention td " provide an improved transformer-coupled signal isolator of Il the type utilizing alterna~ing power and flyback pulses.
I Still another object of this invention is to provide such an I isolator which is relatively inexpensive to manufacture, yet ', reliable in operation, ll .
1, .
1 In accordance with an important aspect of the inven-,~ tion, significantly improved performance is achieved by meansl ¦ of unique circuit arrangements effecting inherent matching o~
the variations of selected corresponding d-c signals in the isolator circuitry. An isolator of the type described herei makes use of an arrangement wherein voltages of relatively I large magnitude are connected in subtractive opposition to I
, develop a resulting difference voltage. In such an arrangement, small non-equal variations in the opposed voltages can produce relatively large percentage changes in the net difference ¦
voltage, and this in turn can cause excessive erxors in the I
li output of the isolator, e.g. due to changes in am~ient temper- ¦
20 li ature. It has been found, however, that such variations can j be substantially reduced by employing simplified matched circuit configurations which assure that selected pairs of 'i d-c signals in the isolator closely -track one another, thereby I to minimize differential efrects, and particularly to reduce ¦
, variations in 1solator performance with changes in temperatur Other objects, aspects and advantages of the invention will in part be pointed out in, and in part apparent from, the ~: O ~.
~ 57571 935 ~
, following detailed description considered together with the accompanying drawing.
BRIEF DESCRIPTION OF THE D~AWING
' FIGURE 1 is a schematic diagram OL a preferred em-,lbodiment of the present invention~
~'I .
I DESCRIPTIO~ OF THE PREFERRED E~BODIMENT .
¦, Referring now to Figure 1, the presently preferrea isolator in accordance with the invention comprises input and ` ioutput sections 10 and 1~ coupled by a trans~ormer 14 having 'one single-turn winding and five identical 8-turn windings.
The output section 12 includes a free-running inductively- , coupLed blocking oscillator generally indicated at 16. This ¦
"oscillator comprises a transistor 18 with its base connected !ito the single-turn winding 20 and its collec~or connected to ,one of the 8-turn windings 22.
.
.l As indicated in the waveform shown directly above ¦Ithe transformer 14 in Figure 1, the blocking oscillator cycle I ¦
iincludes a positive "on" pulse, produced by the power supply 'Ivoltage, fo3,10wed by a negative "flyback" pulse which is unclamped in the oscillator As will he explained, the magni-¦tude of the flyback pulse is modulated in accordance with the ,iinput signal applied to the input section 10 of the isolator.
,,1 1 .1 . I , " ~
~ _5_ 1 , 1 935-04~ 1 57~ l The oscillator on-time is a function of the trans- I
former saturation characteristics, i.e. the time to saturation, whereas the off-time is a function Qf an RC time-constan-t. In one preferred arrangement, the oscillator frequency was approx-imately 200 kH~, with a 0.5 microsecond "on" time and a 4.5 microsecond "off" time. Suitable saturation characteristics jwere obtained in a core made of Ferroxcube 3C8 ferrite.
In the input section 10 of the isolator, there are four half-wave rectifier circuits 30, 32, 34, 36 coupled to Ithe transformer 14. Each of these rectifier circuits consists ~of a diode in series with a filter capacitor. Three of these ! rectifier circuits 30, 32, 34 are connected across a single !
transformer winding 38, but as will be explained the four-th rectifier circuit 36 is connected across a separate trans-former winding 40. Two of the rectirier circuits 30~ 34 are poled to respond to the negative '~flyback" pulse developed in~
the transformer by the blocking oscillator 16 The other two rectifier circuits 32, 36 are oppositely poled, to respond to - the positive "on" power pulse of the oscillator output wave-'form. All of the rectifier circuits develop across their ~respective filter capacitors d-c voltages corresponding to the ,magnitude of whichever pulse (flybacX, or power) they are poled to respond to.
. I .
" ! ~
I I .
1, .
~ 157~71 935.0~2 .1 , The negative d-c voltage developed across the filter capacitor 42 of the first hal-wave recti~ier circuit 30 is applied to the negative supply terminal of an opera-tional amplifier 44, e.g. an IC chip of the typ~ conventionally identified as a 308, and manufactured by a nu~ber of companies.
,The positive supply terminal of this amplilier receives the positive d-c voltage (about 15 volts) developed across the filter capacitor 46 of the second rectifier circuit 32. The Iamplifier input 48 is connected through a resistor (lOOK ohms) I`to the input terminal 50 of the isolator, to receive the ap- ¦
l~plied input signal. The amplifier output terminal 52 is con-nected through a capacitor 54 back to the amplifier input 48 to effect system frequency compensation. The output terminal '52 also is connected to input common 58 by a small resistor l'56 (470 ohms) to accommodate the desired a-c feedback through Icapacitor 5~ while completing the d-c negative supply current return path through the amplifier output suDstantially at common potential.
~ .
' As the input signal applied to the amplifier changes, 'there will be a corresponding change in the d-c supply current "drawn from the negative rectifier voltage-supply circuit 30.
The supply current drawn from that rectirier circuit loads I
down the flyback stroke of the oscillator 16, such that change~
iin the supply current correspondingly modulate the magnitude ~!f the flyback pulse (as indicated in dotted lines in the ,waveform shown in Figure 1). Thus the rectirier circuit 30 115~571 ~35 04~ 1 ' .
~Ifunctions as a modulator, under control of the applied input ¦Isignal This arrangement wherein the negative supply current is used to vary the load on the modulator 30 eliminates the 'need for a separate and additional modulator transistor driven ¦,by the a~lplifier output signal. ' .
The third hal~-wave rectifier circuit 34 is loaded .
by a resistor 60 (220K ohms) returned to the positive supply terminal for the amplifier 44, and produces a negative d-c ~voltage proportional to the magnitude of the modulated flybac~
Ipulse in the transformer 14. That is, the rectifier circuit I
¦34 demodulates the flyback pulse magnitude as controlled by .
the modulator circuit 30. The negative d-c voltage produced I .
by the third rectifier circuit 34 is used as a negative feed- I , ¦back signal for the amplifier 44, to effect correspondence between the amplifier input signal and the modulation signal ~developed by the first rectifier circuit 30. 1 To assure that this feedback signal is at the correct .
voltage level for the input circuit of the 2mpllfier 44, the Inegative d-c signal from the third rectifier circuit 34 is ~Iconnected in series with a positive d-c level-shifting voltagei ¦
j(about 15 volts) produced by the fourth half-wave rectifier circuit 36. This rectifier circuit is loaded by a resistor ~i62 (lOOK ohms) connected directly across the filter capacitor.. I
~The combined voltage signal developed by the two rectifier ~ ¦
icircuits 34, 36 is connected through a feedback resistor 64 1 1 ii . 1.
!l l 1S7571 935. 0~2 "
!`
(~40K) to the input 66 of the amplifier. With this feedback ar~angement, the negative supply current of the amplifier drawn from the modulator rectifier circuit 30 is automatically controlled so as to clamp the flyback pulse to the correct S l, magnitude such that the sum of the voltages produced by the two upper rectifier circui-ts 34 and 36 equals the isolator input voltage.
l .
The isolator as described above has unity gain in ' the input section 10. However, the isolator is arranged so ll that the input section can develop a gain greater than unity~¦
- This is controlled by connecting an external resistor (not shown) between the gain terminal 70 and the input common line 58. With that connection, the amplifier gain will be propor-, tional to the ratio o~ esistances of the feedback resistor. I
64 and the external resistor. I
l It should particularly be noted that in the arranger ,~ ment described above, the modulator circuit 30 and the demod~
- ulator circuit 34 are coupled to the same transformer winding - ~' 38. It has been found that this use of the same winding for i
2~ , both of these circuits provides economy in construction of ¦
the isolator without any adverse effect on performance.
.
~g_ .1 57~71 1 935.042 It also should be noted that the d-c level-shiftinc Ivoltage circuit 36 is energized by a transformer winding 40 which is entlxely separate from the modulate/demodulate winding ll,38. This arrangement is especially advantageous because the ¦llevel-shifting voltage can thereby be developed independently, llof the feedback signal from the corresponding rectifier circu~!t ¦34. Such independent signal development can, as in the prese~t ¦'embodiment, be carried out by the identical type of circuit ¦lused in producing the feedback signal, e.g. the basically simple series-connected half-wave rectifier/filter circuit composed of a diode and a capacitor. This in turn minimizes the number of components which must track with changes in temperature. -By thus reducing the component tracking variables lito only the bare essential elements, and by using identical circuits for developing the two voltages which are to be sub-tractively combined, the effects of temperature-induced drift are significantly reduced, thereby providing more accurate iperfoxmance. In addition, the use of such simplified, low- I
Ipart-count circuitry simultaneously reduces the cost of -,Imanufacturing the isolator.
!
Referring now to the output section 12 of the isolator, l~the transformer 14 includes two further 8-turn windings 80 and ',82 which are identical to the two windings 38 and 40 for the iinput section 10. One of these further windings 80 drives a .1 1 ~35.042 1 ~57571 diode-capacitor half-wave rectifier circuit 86 which is the exact counterpart of the diode-capacitor demodu1ator circuit 34 in the input section, and which also produces a negative ', I,d-c voltage proportional to the magnitudQ of the flyback pulse ,'as controlled by the diode-capacitor modulator circuit 30.
. .
This negative demodulation voltage ~rom the rectifii~r 'circuit 86 is connected in ceries with a fixed-value positive ,d-c bias voltage (e.y. a'bout 15 volts) from another diode-capac1tor rectifier circuit 88 (corresponding directly to Irectifier circuit 36) and coupled to the remaining winding 82., ¦The subtractive combination of these signals develops a d-c input signal of appropriate level for an am~li,ier 90 (e.g.
type 308) which produces the isolator output signal.
~I .
! The lower transformer winding 80 also energizes a f I,supplemental diode-capacitor circuit ga ~hich produces a fixed-,level d-c voltage corresponding to the voltage produced by the~
¦input section rectifier circuit 32. This fixed-level voltage , .
in the outPUt secti.on serves as the reference voltage for the , ,load resistor 96 (220K) of the output demodulation rectifier j`circuit 86, thereby assuring that this demodulation circuit ,I!performs in a fashion identical to that of the reedback ,~demodulator circuit 34, so that the -two demodulator signals will trac~ one another very closely.
il I
., - 1~ 935.0~2 l l ll 1 15757~ ~ I
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A load resistor 98 (lOOK) is coupled across the ~filter capacitor of the bias voltaye rectifier circuit 88 to leffect identical correspondence with the level-shifting recti-llfier circuit 36 in the input section 10. The combined ~emod-5 ¦1 ulation and hias voltage signal is directed through an input¦Iresistor 100 (lOOK) to an input terminal 102 of the amplif.ier 90~ The external circuitry for this amplifier also includes appropriate filter and compensation capacitors as shown.
I Although a specific preferred embodiment of the 'invention has been disclosed herein in detail, it is to be understood that this is for the purpose of illustrating the .
invention, and should not be construed as necessarily limiting .
'the scope of the invention, since it is appar~nt that many .
,,changes can be made to the disclosed structure by those skilleid in the art to suit particular appllcations. ~
. I, - !
~.
. -12- i .1 ', '.
1.
, .
the isolator without any adverse effect on performance.
.
~g_ .1 57~71 1 935.042 It also should be noted that the d-c level-shiftinc Ivoltage circuit 36 is energized by a transformer winding 40 which is entlxely separate from the modulate/demodulate winding ll,38. This arrangement is especially advantageous because the ¦llevel-shifting voltage can thereby be developed independently, llof the feedback signal from the corresponding rectifier circu~!t ¦34. Such independent signal development can, as in the prese~t ¦'embodiment, be carried out by the identical type of circuit ¦lused in producing the feedback signal, e.g. the basically simple series-connected half-wave rectifier/filter circuit composed of a diode and a capacitor. This in turn minimizes the number of components which must track with changes in temperature. -By thus reducing the component tracking variables lito only the bare essential elements, and by using identical circuits for developing the two voltages which are to be sub-tractively combined, the effects of temperature-induced drift are significantly reduced, thereby providing more accurate iperfoxmance. In addition, the use of such simplified, low- I
Ipart-count circuitry simultaneously reduces the cost of -,Imanufacturing the isolator.
!
Referring now to the output section 12 of the isolator, l~the transformer 14 includes two further 8-turn windings 80 and ',82 which are identical to the two windings 38 and 40 for the iinput section 10. One of these further windings 80 drives a .1 1 ~35.042 1 ~57571 diode-capacitor half-wave rectifier circuit 86 which is the exact counterpart of the diode-capacitor demodu1ator circuit 34 in the input section, and which also produces a negative ', I,d-c voltage proportional to the magnitudQ of the flyback pulse ,'as controlled by the diode-capacitor modulator circuit 30.
. .
This negative demodulation voltage ~rom the rectifii~r 'circuit 86 is connected in ceries with a fixed-value positive ,d-c bias voltage (e.y. a'bout 15 volts) from another diode-capac1tor rectifier circuit 88 (corresponding directly to Irectifier circuit 36) and coupled to the remaining winding 82., ¦The subtractive combination of these signals develops a d-c input signal of appropriate level for an am~li,ier 90 (e.g.
type 308) which produces the isolator output signal.
~I .
! The lower transformer winding 80 also energizes a f I,supplemental diode-capacitor circuit ga ~hich produces a fixed-,level d-c voltage corresponding to the voltage produced by the~
¦input section rectifier circuit 32. This fixed-level voltage , .
in the outPUt secti.on serves as the reference voltage for the , ,load resistor 96 (220K) of the output demodulation rectifier j`circuit 86, thereby assuring that this demodulation circuit ,I!performs in a fashion identical to that of the reedback ,~demodulator circuit 34, so that the -two demodulator signals will trac~ one another very closely.
il I
., - 1~ 935.0~2 l l ll 1 15757~ ~ I
~! i , . . .
A load resistor 98 (lOOK) is coupled across the ~filter capacitor of the bias voltaye rectifier circuit 88 to leffect identical correspondence with the level-shifting recti-llfier circuit 36 in the input section 10. The combined ~emod-5 ¦1 ulation and hias voltage signal is directed through an input¦Iresistor 100 (lOOK) to an input terminal 102 of the amplif.ier 90~ The external circuitry for this amplifier also includes appropriate filter and compensation capacitors as shown.
I Although a specific preferred embodiment of the 'invention has been disclosed herein in detail, it is to be understood that this is for the purpose of illustrating the .
invention, and should not be construed as necessarily limiting .
'the scope of the invention, since it is appar~nt that many .
,,changes can be made to the disclosed structure by those skilleid in the art to suit particular appllcations. ~
. I, - !
~.
. -12- i .1 ', '.
1.
, .
Claims (28)
input and output sections;
a transformer coupling said input and output sections;
a first amplifier forming part of said input section to receive an input signal;
a second amplifier forming part of said output section to develop an output signal;
means for generating in said transformer an alter-nating pulse signal comprising a power pulse followed by a flyback pulse;
first winding means for said transformer;
a first diode/capacitor half-wave rectifier circuit forming part of said input section and coupled to said first winding means;
said first rectifier circuit being poled to respond to said flyback pulse;
means coupling said first amplifier to said first half-wave rectifier circuit to effect modulation of the magni-tude of said flyback pulse in accordance with said input signal;
a second diode/capacitor half-wave rectifier circuit forming part of said input section and coupled to said first winding means;
said second rectifier circuit being poled to respond to said power pulse to produce a d-c power voltage for said first amplifier;
a third diode/capacitor half wave rectifier circuit forming part of said input section and coupled to said first winding means;
935.042
1. cont.:
said third rectifier circuit being poled to respond to said flyback pulse to develop a d-c negative feedback sig-nal for said first amplifier;
second winding means for said transformer separate from said first winding means;
a fourth diode/capacitor half-wave rectifier circuit forming part of said input section and coupled to said second winding means;
said fourth rectifier circuit being poled to respond to said power pulse to produce a d-c level shifting voltage;
means connecting said level-shifting voltage in series with said feedback signal to provide a feedback voltage level within the operating range of said first amplifier;
third winding means for said transformer separate from said first and second winding means; and diode/capacitor rectifier means coupled to said third winding means to develop an input signal for said second amplifier.
said third rectifier circuit being poled to respond to said flyback pulse to develop a d-c negative feedback sig-nal for said first amplifier;
second winding means for said transformer separate from said first winding means;
a fourth diode/capacitor half-wave rectifier circuit forming part of said input section and coupled to said second winding means;
said fourth rectifier circuit being poled to respond to said power pulse to produce a d-c level shifting voltage;
means connecting said level-shifting voltage in series with said feedback signal to provide a feedback voltage level within the operating range of said first amplifier;
third winding means for said transformer separate from said first and second winding means; and diode/capacitor rectifier means coupled to said third winding means to develop an input signal for said second amplifier.
2. Apparatus as claimed in claim 1, wherein said first winding means comprises at least one multi-turn winding;
said first and third half-wave rectifier circuits both being coupled to said multi-turn winding.
935.042
said first and third half-wave rectifier circuits both being coupled to said multi-turn winding.
935.042
3. Apparatus as claimed in claim 2, wherein said second half-wave rectifier circuit also is coupled to said multi-turn winding,
4. Apparatus as claimed in claim 1, wherein said diode/capacitor rectifier means in said output section comprises fifth and sixth half-wave rectifier circuits;
said fifth rectifier circuit being poled to respond to said flyback pulse to produce a d-c modulation signal;
said sixth rectifier circuit being poled to respond to said power pulse to produce a d-c bias signal; and means connecting said d-c modulation signal in series with said bias signal to produce an input signal for said second amplifier.
said fifth rectifier circuit being poled to respond to said flyback pulse to produce a d-c modulation signal;
said sixth rectifier circuit being poled to respond to said power pulse to produce a d-c bias signal; and means connecting said d-c modulation signal in series with said bias signal to produce an input signal for said second amplifier.
5. Apparatus as claimed in claim 4, wherein said third winding means comprises a pair of separate multi-turn windings;
said fifth and sixth rectifier circuits being coupled respectively to said pair of separate windings.
6. Apparatus as claimed in claim 5, including a load connected between the feedback signal developed by said third rectifier and a fixed reference voltage in said input section and
said fifth and sixth rectifier circuits being coupled respectively to said pair of separate windings.
6. Apparatus as claimed in claim 5, including a load connected between the feedback signal developed by said third rectifier and a fixed reference voltage in said input section and
6. cont.:
a second load connected between the d-c modulation signal developed by said fifth rectifier circuit and a fixed reference voltage in said output section.
a second load connected between the d-c modulation signal developed by said fifth rectifier circuit and a fixed reference voltage in said output section.
7. Apparatus as claimed in claim 6, wherein each of said loads is a resistor.
8. Apparatus as claimed in claim 7, wherein said fixed reference voltage in the input section is said d-c power vol-tage developed by said second rectifier circuit, a seventh diode/capacitor rectifier in said output section and coupled to one of said pair of windings;
said seventh rectifier circuit being identical to said second rectifier circuit to produce a corresponding d-c voltage to serve as said fixed reference voltage in said output section.
said seventh rectifier circuit being identical to said second rectifier circuit to produce a corresponding d-c voltage to serve as said fixed reference voltage in said output section.
9. Apparatus as claimed in claim 1, wherein the output of said first amplifier is connected to circuit common for said input section;
the negative voltage developed by said first diode/
capacitor rectifier circuit being connected to the negative supply terminal of said first amplifier and responsive to the current drawn by said first amplifier so as to modulate the magnitude of said flyback pulse in accordance with the magni-tude of the input signal applied to said first amplifier.
935.042 10. An electrical signal isolator comprising:
input and output sections;
a transformer coupling said input and output sections;
a first amplifier forming part of said input section to receive an input signal;
a second amplifier forming part of said output section to develop an output signal;
means for generating in said transformer an alter-nating pulse signal comprising a power pulse followed by a flyback pulse;
first winding means for said transformer comprising at least one multi-turn winding;
a first diode/capacitor half-wave rectifier/filter circuit forming part of said input section and coupled to said multi-turn winding;
said first rectifier/filter circuit being poled to respond to said flyback pulse;
means coupling said first amplifier to said first half-wave rectifier/filter circuit to effect modulation of the magnitude of said flyback pulse in accordance with said input signal;
a second diode/capacitor half-wave rectifier/filter circuit forming part of said input section and coupled to said winding means;
said second rectifier/filter circuit being poled to respond to said power pulse to produce a d-c power voltage for said first amplifier;
the negative voltage developed by said first diode/
capacitor rectifier circuit being connected to the negative supply terminal of said first amplifier and responsive to the current drawn by said first amplifier so as to modulate the magnitude of said flyback pulse in accordance with the magni-tude of the input signal applied to said first amplifier.
935.042 10. An electrical signal isolator comprising:
input and output sections;
a transformer coupling said input and output sections;
a first amplifier forming part of said input section to receive an input signal;
a second amplifier forming part of said output section to develop an output signal;
means for generating in said transformer an alter-nating pulse signal comprising a power pulse followed by a flyback pulse;
first winding means for said transformer comprising at least one multi-turn winding;
a first diode/capacitor half-wave rectifier/filter circuit forming part of said input section and coupled to said multi-turn winding;
said first rectifier/filter circuit being poled to respond to said flyback pulse;
means coupling said first amplifier to said first half-wave rectifier/filter circuit to effect modulation of the magnitude of said flyback pulse in accordance with said input signal;
a second diode/capacitor half-wave rectifier/filter circuit forming part of said input section and coupled to said winding means;
said second rectifier/filter circuit being poled to respond to said power pulse to produce a d-c power voltage for said first amplifier;
10. cont.:
a third diode/capacitor half-wave rectifier/filter.
circuit forming part of said input section and coupled to said multi-turn winding;
said third rectifier/filter circuit being poled to respond to said flyback pulse to develop a d-c negative feed-back signal for said first amplifier;
a fourth diode/capacitor half-wave rectifier/filter circuit forming part of said input section and coupled to said first winding means;
said fourth rectifier/filter circuit being poled to respond to said power pulse to produce a d-c level-shifting voltage;
means connecting said level-shifting voltages in series with said feedback signal to provide a feedback voltage level within the operating range of said first amplifier;
second winding means for said transformer separate from said first winding means; and diode/capacitor rectifier means coupled to said second winding means to develop an input signal for said second amplifier.
a third diode/capacitor half-wave rectifier/filter.
circuit forming part of said input section and coupled to said multi-turn winding;
said third rectifier/filter circuit being poled to respond to said flyback pulse to develop a d-c negative feed-back signal for said first amplifier;
a fourth diode/capacitor half-wave rectifier/filter circuit forming part of said input section and coupled to said first winding means;
said fourth rectifier/filter circuit being poled to respond to said power pulse to produce a d-c level-shifting voltage;
means connecting said level-shifting voltages in series with said feedback signal to provide a feedback voltage level within the operating range of said first amplifier;
second winding means for said transformer separate from said first winding means; and diode/capacitor rectifier means coupled to said second winding means to develop an input signal for said second amplifier.
11. Apparatus as claimed in claim 10, wherein said first and third rectifier/filter circuits each consists of a series-connected diode-and-capacitor connected together across said multi-turn winding.
935.042
935.042
12. Apparatus as claimed in claim 10, wherein said first winding means includes a second multi-turn winding;
said fourth rectifier/filter circuit being coupled to said second multi-turn winding.
said fourth rectifier/filter circuit being coupled to said second multi-turn winding.
13. Apparatus as claimed in claim 12, wherein said second winding means comprises third and fourth multi-turn windings;
said diode/capacitor rectifier means comprising fifth and sixth half-wave rectifier/filter circuits coupled respectively to said third and fourth multi-turn windings;
said fifth rectifier/filter circuit being poled to respond to said flyback pulse to develop a d-c modulation signal;
said sixth rectifier/filter circuit being poled to respond to said power pulse to produce a d-c bias signal;
means connecting said d-c modulation signal in series with said bias signal and to the input of said second amplifier.
said diode/capacitor rectifier means comprising fifth and sixth half-wave rectifier/filter circuits coupled respectively to said third and fourth multi-turn windings;
said fifth rectifier/filter circuit being poled to respond to said flyback pulse to develop a d-c modulation signal;
said sixth rectifier/filter circuit being poled to respond to said power pulse to produce a d-c bias signal;
means connecting said d-c modulation signal in series with said bias signal and to the input of said second amplifier.
14. Apparatus as claimed in claim 13, wherein said third and fourth rectifier/filter circuits are identical to, respec-tively, said fifth and sixth rectifier/filter circuits.
15. Apparatus as claimed in claim 14, wherein said first and second multi-turn windings are identical to, respectively, said third and fourth multi-turn windings.
16. In an electrical signal isolator of the type including input and output sections, a transformer coupling said input and output sections, a first amplifier forming part of said input section to receive an input signal, a second amplifier forming part of said output section to develop an output signal, means for generating in said transformer an alternating pulse signal comprising a power pulse followed by a flyback pulse, that improvement comprising:
a first multi-turn winding for said transformer;
a first series-connected diode-capacitor rectifier/
filter circuit connected across said first winding and poled to respond to said flyback pulse;
means coupling said first amplifier to said first rectifier circuit to effect modulation of the magnitude of said flyback pulse in accordance with said input signal;
a second series-connected diode-capacitor rectifier/
filter circuit connected across said first winding and poled to respond to said power pulse to produce a d-c power voltage for said first amplifier;
a third series-connected diode-capacitor rectifier/
filter circuit connected across said first winding and poled to respond to said flyback pulse to develop a d-c negative feedback signal for said first amplifier;
a second multi-turn winding for said transformer separate from said first winding;
935.042
16. In an electrical signal isolator of the type including input and output sections, a transformer coupling said input and output sections, a first amplifier forming part of said input section to receive an input signal, a second amplifier forming part of said output section to develop an output signal, means for generating in said transformer an alternating pulse signal comprising a power pulse followed by a flyback pulse, that improvement comprising:
a first multi-turn winding for said transformer;
a first series-connected diode-capacitor rectifier/
filter circuit connected across said first winding and poled to respond to said flyback pulse;
means coupling said first amplifier to said first rectifier circuit to effect modulation of the magnitude of said flyback pulse in accordance with said input signal;
a second series-connected diode-capacitor rectifier/
filter circuit connected across said first winding and poled to respond to said power pulse to produce a d-c power voltage for said first amplifier;
a third series-connected diode-capacitor rectifier/
filter circuit connected across said first winding and poled to respond to said flyback pulse to develop a d-c negative feedback signal for said first amplifier;
a second multi-turn winding for said transformer separate from said first winding;
935.042
16. cont.:
a fourth series-connected diode-capacitor rectifier/
filter circuit connected across said second winding and poled to respond to said power pulse to produce a d-c level-shifting voltage;
means connecting said level-shifting voltage in series withsaid feedback signal to provide a feedback voltage having a level within the operating range of said first ampli-fier;
a third multi-turn winding for said transformer identical to said first winding;
a fifth series-connected diode-capacitor rectifier/
filter circuit connected across said third winding and poled to respond to said flyback pulse to produce a d-c modulation signal;
a fourth multi-turn winding for said transformer identical to said second winding;
a sixth series-connected diode-capacitor rectifier/
filter circuit connected across said fourth winding to produce d-c bias signal; and means connecting said d-c modulation signal in series with said bias signal to produce an input signal for said second amplifier.
935.042
a fourth series-connected diode-capacitor rectifier/
filter circuit connected across said second winding and poled to respond to said power pulse to produce a d-c level-shifting voltage;
means connecting said level-shifting voltage in series withsaid feedback signal to provide a feedback voltage having a level within the operating range of said first ampli-fier;
a third multi-turn winding for said transformer identical to said first winding;
a fifth series-connected diode-capacitor rectifier/
filter circuit connected across said third winding and poled to respond to said flyback pulse to produce a d-c modulation signal;
a fourth multi-turn winding for said transformer identical to said second winding;
a sixth series-connected diode-capacitor rectifier/
filter circuit connected across said fourth winding to produce d-c bias signal; and means connecting said d-c modulation signal in series with said bias signal to produce an input signal for said second amplifier.
935.042
17. Apparatus as claimed in claim 16, wherein said fifth rectifier/filter circuit is identical to said third rectifier/
filter circuit, and said sixth rectifier/filter circuit is identical to said fourth rectifier/filter circuit.
filter circuit, and said sixth rectifier/filter circuit is identical to said fourth rectifier/filter circuit.
18. Apparatus as claimed in claim 17, wherein all of said windings are identical.
19. Apparatus as claimed in claim 18, wherein all of said rectifier/filter circuits are in configuration.
20. Apparatus as claimed in claim 19, including a seventh rectifier/filter circuit identical to said fourth rectifier/filter circuit and connected across one of said third or fourth windings.
935.042
935.042
21. In an electrical signal isolator of the type including input and output sections, a transformer having first and second winding means coupling said input and output sections, a first amplifier forming part of said input section to receive an input signal, a second amplifier forming part of said output section to develop an output signal, means for generating in said transformer winding means an alternating pulse signal comprising a power pulse followed by a flyback pulse, that improvement in such an isolator comprising:
first diode-capacitor rectifier means coupled to said first winding means and poled to respond to said flyback pulse to produce a corresponding d-c voltage;
means connecting said corresponding d-c voltage to a supply terminal of said first amplifier to provide for modulation of the magnitude of said flyback pulse in accord-ance with the amount of supply current drawn by said first amplifier;
second diode-capacitor rectifier means coupled to said first winding means to develop a d-c negative feedback signal for said first amplifier; and third diode-capacitor rectifier means coupled to said second winding means to produce an input signal for said second amplifier corresponding to the modulated magnitude of said flyback pulse.
935.042
first diode-capacitor rectifier means coupled to said first winding means and poled to respond to said flyback pulse to produce a corresponding d-c voltage;
means connecting said corresponding d-c voltage to a supply terminal of said first amplifier to provide for modulation of the magnitude of said flyback pulse in accord-ance with the amount of supply current drawn by said first amplifier;
second diode-capacitor rectifier means coupled to said first winding means to develop a d-c negative feedback signal for said first amplifier; and third diode-capacitor rectifier means coupled to said second winding means to produce an input signal for said second amplifier corresponding to the modulated magnitude of said flyback pulse.
935.042
22. Apparatus as claimed in claim 21, wherein the output of said first amplifier is connected to the common lead of said input section, to hold the amplifier output level at a substantially constant d-c value.
23. Apparatus as claimed in claim 22, including a resistor connecting said amplifier output to common; and a capacitor coupling said amplifier output to the amplifier input to effect system compensation.
935.042 2. In an electrical signal isolator of the type includ-ing input and output sections, a transformer coupling said input and output sections, a first amplifier forming part of said input section to receive an input signal, a second ampli-fier forming part of said output section to develop an output signal; that improvement in such isolator comprising:
a transistor having a base, collector, and emitter;
first winding means for said transformer coupled between said base and said emitter;
second winding means for said transformer including at least one multi-turn winding coupled between said emitter and said collector;
d-c power supply means coupled to said emitter and said one multi-turn winding to energize said transistor and said windings to provide a free-running inductance-coupled blocking oscillator producing a power pulse followed by flyback pulse;
third winding means for said transformer;
first diode-capacitor rectifier means coupled to said third winding means and poled to respond to said flyback pulse;
means connecting said first amplifier to said first rectifier means to effect modulation of the magnitude of said flyback pulse in accordance with the input signal applied to said first amplifier;
second diode-capacitor rectifier means coupled to said third winding means to develop a d-c negative feedback signal for said first amplifier;
935.042
935.042 2. In an electrical signal isolator of the type includ-ing input and output sections, a transformer coupling said input and output sections, a first amplifier forming part of said input section to receive an input signal, a second ampli-fier forming part of said output section to develop an output signal; that improvement in such isolator comprising:
a transistor having a base, collector, and emitter;
first winding means for said transformer coupled between said base and said emitter;
second winding means for said transformer including at least one multi-turn winding coupled between said emitter and said collector;
d-c power supply means coupled to said emitter and said one multi-turn winding to energize said transistor and said windings to provide a free-running inductance-coupled blocking oscillator producing a power pulse followed by flyback pulse;
third winding means for said transformer;
first diode-capacitor rectifier means coupled to said third winding means and poled to respond to said flyback pulse;
means connecting said first amplifier to said first rectifier means to effect modulation of the magnitude of said flyback pulse in accordance with the input signal applied to said first amplifier;
second diode-capacitor rectifier means coupled to said third winding means to develop a d-c negative feedback signal for said first amplifier;
935.042
24. cont.:
third diode-capacitor rectifier means coupled to said third winding means and poled to respond to said power pulse to produce a d-c power supply voltage for said first amplifier; and fourth diode-capacitor rectifier means coupled to said second winding means to produce an input signal for said second amplifier corresponding to the modulated magnitude of said flyback pulse.
third diode-capacitor rectifier means coupled to said third winding means and poled to respond to said power pulse to produce a d-c power supply voltage for said first amplifier; and fourth diode-capacitor rectifier means coupled to said second winding means to produce an input signal for said second amplifier corresponding to the modulated magnitude of said flyback pulse.
25. Apparatus as claimed in claim 24, wherein said first winding means is a single-turn winding.
26. Apparatus as claimed in claim 24, including a first capacitor connected between said first winding means and said emitter, and a second capacitor connected between said emitter and said one multi-turn winding.
935.042
935.042
27. In an electrical signal isolator of the type includ-ing input and output sections, a transformer having first and second winding means coupling said input and output sections, a first amplifier forming part of said input section to receive an input signal, a second amplifier forming part of said output section to develop an output signal, means for generating in said transformer winding means an alternating pulse signal comprising a power pulse followed by a flyback pulse; a diode-capacitor circuit coupled to one of said winding means for mod-ulating the magnitude of said flyback pulse in accordance with the input signal applied to said first amplifier; the improved method of modulating said flyback pulse comprising the steps of:
developing a d-c voltage on the capacitor of said diode-capacitor circuit responsive to said flyback pulse; and altering the magnitude of said flyback pulse by drawing from said d-c voltage a supply current for said ampli-fier which varies in accordance with said applied input signal
developing a d-c voltage on the capacitor of said diode-capacitor circuit responsive to said flyback pulse; and altering the magnitude of said flyback pulse by drawing from said d-c voltage a supply current for said ampli-fier which varies in accordance with said applied input signal
28. The method of claim 27, including the step of hold-ing the output of said first amplifier at least substantially constant while said supply current is varied in accordance with said input signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/108,540 US4286225A (en) | 1979-12-31 | 1979-12-31 | Isolation amplifier |
| US108,540 | 1979-12-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1157571A true CA1157571A (en) | 1983-11-22 |
Family
ID=22322786
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000367616A Expired CA1157571A (en) | 1979-12-31 | 1980-12-29 | Isolation amplifier |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4286225A (en) |
| JP (1) | JPS56102106A (en) |
| CA (1) | CA1157571A (en) |
| DE (1) | DE3047523A1 (en) |
| FR (1) | FR2472879A1 (en) |
| GB (2) | GB2067041B (en) |
| NL (1) | NL8007101A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7064442B1 (en) | 2003-07-02 | 2006-06-20 | Analog Devices, Inc. | Integrated circuit package device |
| US7718967B2 (en) * | 2005-01-26 | 2010-05-18 | Analog Devices, Inc. | Die temperature sensors |
| US8487260B2 (en) * | 2005-01-26 | 2013-07-16 | Analog Devices, Inc. | Sensor |
| US7692148B2 (en) * | 2005-01-26 | 2010-04-06 | Analog Devices, Inc. | Thermal sensor with thermal barrier |
| US7807972B2 (en) * | 2005-01-26 | 2010-10-05 | Analog Devices, Inc. | Radiation sensor with cap and optical elements |
| US7435964B2 (en) | 2005-01-26 | 2008-10-14 | Analog Devices, Inc. | Thermal sensor with increased sensitivity |
| US7557655B2 (en) * | 2007-11-05 | 2009-07-07 | Schweitzer Engineering Laboratories, Inc. | Systems and methods for isolating an analog signal |
| US7889041B2 (en) * | 2007-11-05 | 2011-02-15 | Schweitzer Engineering Laboratories, Inc. | Systems and methods for forming an isolated transformer |
| US8523427B2 (en) | 2008-02-27 | 2013-09-03 | Analog Devices, Inc. | Sensor device with improved sensitivity to temperature variation in a semiconductor substrate |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3988690A (en) * | 1973-10-04 | 1976-10-26 | Tektronix, Inc. | Amplifier circuit having a floating input stage |
| JPS52108758U (en) * | 1976-02-16 | 1977-08-18 | ||
| JPS52108758A (en) * | 1976-03-09 | 1977-09-12 | Mitsubishi Electric Corp | Insulation amplifier |
| US4066974A (en) * | 1976-07-23 | 1978-01-03 | The Birtcher Corporation | Isolation amplifier |
| US4152660A (en) * | 1978-03-30 | 1979-05-01 | Burr-Brown Research Corporation | Isolation amplifier |
-
1979
- 1979-12-31 US US06/108,540 patent/US4286225A/en not_active Expired - Lifetime
-
1980
- 1980-12-17 DE DE19803047523 patent/DE3047523A1/en not_active Withdrawn
- 1980-12-17 JP JP17863780A patent/JPS56102106A/en active Granted
- 1980-12-29 CA CA000367616A patent/CA1157571A/en not_active Expired
- 1980-12-30 GB GB8041517A patent/GB2067041B/en not_active Expired
- 1980-12-30 NL NL8007101A patent/NL8007101A/en not_active Application Discontinuation
- 1980-12-31 FR FR8027885A patent/FR2472879A1/en active Pending
-
1984
- 1984-02-09 GB GB08403392A patent/GB2136650B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2136650A (en) | 1984-09-19 |
| GB2136650B (en) | 1985-03-27 |
| JPH0143482B2 (en) | 1989-09-21 |
| GB8403392D0 (en) | 1984-03-14 |
| GB2067041A (en) | 1981-07-15 |
| DE3047523A1 (en) | 1981-09-17 |
| US4286225A (en) | 1981-08-25 |
| NL8007101A (en) | 1981-08-03 |
| JPS56102106A (en) | 1981-08-15 |
| GB2067041B (en) | 1984-10-03 |
| FR2472879A1 (en) | 1981-07-03 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |